S66 PSYCHOLOGY. 



which the adept thus finds himself swept on to, he knows 

 not how or why. 



A physiological conclusion remains to he draion. If the 

 principles laid down in Chapter XIV are true, then it fol- 

 lows that the great cerebral difference between habitual and 

 reasoned thinking must be this : that in the former an entire 

 system of cells vibrating at any one moment discharges in 

 its totality into another entire system, and that the order 

 of the discharges tends to be a constant one in time ; whilst 

 in the latter a part of the prior system still keeps vibrating 

 in the midst of the subsequent system, and the order — 

 which part this shall be, and what shall be its concomitants 

 in the subsequent system — has little tendency to fixedness 

 in time. This physical selection, so to call it, of one part 

 to vibrate persistently whilst the others rise and subside, 

 we found, in the chapter in question, to be the basis of 

 similar association. (See especially j^p. 578-81.) It would 

 seem to be but a minor degree of that still more urgent 

 and importunate localized vibration which we can easiest 

 conceive to underlie the mental fact of interest, attention, 

 or dissociation. In terms of the brain-process, then, all 

 these mental facts resolve themselves into a single peculi- 

 arity : that of indeterminateness of connection between 

 the different tracts, and tendency of action to focalize 

 itself, so to speak, in small localities which vary infinitely 

 at different times, and from which irradiation may pro- 

 ceed in countless shifting ways. (Compare figure 80, p. 

 347.) To discover, or (what more befits the present stage 

 ■of nerve-physiology) to adumbrate by some possible guess, 

 on what chemical or molecular-mechanical fact this instable 

 equilibrium of the human brain may depend, should be the 

 next task of the physiologist who ponders over the passage 

 from brute to man. Whatever the physical peculiarity in 

 -question may be, it is the cause why a man, whose brain 

 lias it, reasons so much, whilst his horse, whose brain lacks 

 it, reasons so little. We can but bequeath the problem to 

 abler hands than our own. 



But, meanwhile, this mode of stating the matter suggests 

 a couple of other inferences. The first is brief. If focali" 



